The present invention relates generally to conveyor rolls and, more particularly, to conveyor rolls for moving glass sheets between opposed arrays of cooling fluid directing tubes.
In one known commercial production method for fabricating curved or bent glass sheets in large quantities, such as glazing closures for automobiles and the like, the sheets are supported in a horizontal plane and advanced in a horizontal path on externally driven roll-type conveyors. The sheets are conveyed successively through a heating area, a bending area and a heat treating area for annealing or tempering the bent sheets. The heated glass sheets are advanced from the heating furnace into the bending area and accurately located therein between complemental upper and lower shaping members by the engagement of the leading edges thereof with locating stops positioned in the path of movement of the advancing sheets. When properly oriented, the sheet is engaged along its marginal edge portions by the lower press member and lifted from the conveyor rolls for pressing between the complemental shaping surfaces of the press members into the desired curvature.
It has been found desirable to employ in the bending area a series of conveyor rolls having arcuately shaped central portions which normally are disposed in an upper common horizontal plane for supporting a flat sheet of heat-softened glass prior to bending and which are pivotable into a lower position at angular attitudes or planes relative to the common horizontal plane out of engagement with said flat sheet upon engagement thereof along its marginal edge portion by the shaping rail of the upwardly movable lower press member. In their lower attitudes, these rolls conjointly define a curved surface complementary to the curvature imparted to the sheet for receiving the same after bending and which serve to preserve such curvature as the bent sheet is advanced out of the bending area. These rolls, which are of a two-piece construction comprised of a fixed inner core and a rotatable outer sleeve, are disclosed in detail and claimed in U.S. Pat. Ser. No. 3,905,794.
In the usual roll construction of the above type, the fixed inner core of the roll is attached at one end thereof to a stub shaft extending through axially spaced bushings mounted in a rotatable drive member which is connected to the rotatable sleeve of the roll. During removal and replacement of the curved inner core from and into the outer sleeve, which is required in the bending area each time a production run of differently configured sheets is contemplated, problems were encountered in properly withdrawing and then inserting the associated stub shaft from and through the bushings without damaging the latter. Moreover, even slight wear of these bushings caused erratic and unbalanced rotation of the associated rolls.
U.S. Pat. Ser. No. 4,167,997 discloses a quick connect-disconnect coupling assembly detachably connecting the inner core member of a composite type conveyor roll to its mounting. The coupling assembly includes a tubular drive extension, a first coupling section rigidly secured to the core member and a second coupling section mounted with the drive extension. Such a coupling assembly facilitated rapid and easy conveyor roll core removal and replacement without disturbing other components associated with the roll.
As disclosed in U.S. Pat. Ser. No. 4,167,997, after the bending operation, sheets of glass are transferred through a tempering section where their temperature is rapidly reduced to produce the proper temper in the glass. The tempering section includes a chilling means comprising upper and lower blastheads disposed above and below the path of movement of the glass sheets, each being provided with a plurality of manifold sections having a series of tubes to direct opposed streams of cooling fluid, such as air, toward and against the opposite surfaces of the glass sheets. As the demands for higher quality tempered thin glass and faster production have increased, it has been determined that one method of meeting these demands is to space the cooling tubes closer together. However, the conveyor rolls according to the prior art tend to block a substantial portion of the air flow as the glass sheets move through the tempering section.